<TABLE> <S> <C>

<PAGE>
<ARTICLE> 5
<RESTATED> 
       
<S>                             <C>                     <C>                     <C>
<PERIOD-TYPE>                   YEAR                   YEAR                   YEAR
<FISCAL-YEAR-END>                          DEC-31-1997             DEC-31-1996             DEC-31-1995
<PERIOD-START>                             JAN-01-1997             JAN-01-1996             JAN-01-1995
<PERIOD-END>                               DEC-31-1997             DEC-31-1996             DEC-31-1995
<CASH>                                         150,890                 366,677                 514,610
<SECURITIES>                                         0                       0                       0
<RECEIVABLES>                                1,026,967               1,554,348                 822,395
<ALLOWANCES>                                         0                       0                       0
<INVENTORY>                                          0                       0                       0
<CURRENT-ASSETS>                             2,036,145               3,644,720               2,038,452
<PP&E>                                      29,210,699              27,889,580              22,176,136
<DEPRECIATION>                              15,975,838              14,076,100              11,816,754
<TOTAL-ASSETS>                              17,620,483              18,976,646              14,123,352
<CURRENT-LIABILITIES>                        1,564,683               3,268,428               1,905,703
<BONDS>                                      9,115,370               7,166,421               4,524,617
<PREFERRED-MANDATORY>                                0                       0                       0
<PREFERRED>                                          0                       0                       0
<COMMON>                                         4,463                   4,401                   4,394
<OTHER-SE>                                   6,714,563               8,172,859               7,643,638
<TOTAL-LIABILITY-AND-EQUITY>                17,620,483              18,976,646              14,123,352
<SALES>                                      6,396,249               6,958,491               5,147,033
<TOTAL-REVENUES>                             7,095,395               7,240,030               5,417,085
<CGS>                                        3,088,886               2,981,837               2,509,854
<TOTAL-COSTS>                                8,725,584               6,465,181               6,530,357
<OTHER-EXPENSES>                                     0                       0                       0
<LOSS-PROVISION>                                     0                       0                       0
<INTEREST-EXPENSE>                             970,430                 722,447                 611,587
<INCOME-PRETAX>                            (2,600,619)                  52,402             (1,113,272)
<INCOME-TAX>                                 (717,237)                  30,280               (376,241)
<INCOME-CONTINUING>                        (1,883,382)                  22,122               (737,031)
<DISCONTINUED>                                       0                       0                       0
<EXTRAORDINARY>                                      0                       0                       0
<CHANGES>                                            0                       0                       0
<NET-INCOME>                               (1,883,382)                  22,122               (737,031)
<EPS-PRIMARY>                                    (.42)                     .01                   (.22)
<EPS-DILUTED>                                    (.42)                     .01                   (.22)
        

</TABLE>